UV Scented Ink – Photoinitiator
In addition to the pursuit of visual beauty in printing, people in the sense of smell is also a breakthrough in the direction of scented printing. Fragrance printing is the earliest in the printing ink or paper to add spices to get the flavor, this method is simple, but not easy to last. Later, due to the invention of microcapsule technology, the spice will be sealed into the microcapsule, and made into ink for printing. As the spice is closed by the microcapsules, Xu Xu emitted, so the print can be long-lasting fragrance. In the UV scented ink curing with a finger gently rubbed, you can smell the rich fragrance. Scented printing is mainly used in magazines, advertisements, flyers, manuals, postcards, menu, calendars, etc. It can also be used for textile printing.
UV scented ink is a kind of microencapsulated ink, is added in the UV ink microcapsules and made of a special ink. Microencapsulation technology is a new technology developed in the mid-20th century. It is in the material (solid, liquid, gaseous) particles (droplets) around a layer of natural polymers or synthetic polymer materials coated with a film, forming a very small capsule. Microcapsules have many special properties, it can store the microfine state of the substance and release it when needed, but also can change the color, shape, quality, volume, solubility, reactivity, durability, pressure-sensitive, heat-sensitive and photosensitive. Therefore, microencapsulation technology is widely used in medicine, food, cosmetics, detergents, pesticides, fertilizers, printing and other industries. The combination of microencapsulation technology and ink production and manufacturing technology for the development of printing ink provides new ideas, not only to promote the development of new varieties of ink, such as scented ink, foam ink, liquid crystal ink, etc., but also produces a number of new printing processes, improve the added value of packaging and printing products.
The diameter of microcapsules is generally in the micron to millimeter level, the particle size of 2 ~ 200μm, if the particle size <1μm called nanocapsules. Packed in the microcapsule inside the material is called the capsule core, the core material inside the capsule core can be liquid, solid or gas, can be a single nucleus can also be a multi-core. The outer skin of the microcapsule, i.e., the membrane formed by the polymer film-forming material is called the wall material, or called the outer membrane, the envelope, the thickness of the capsule wall is 0.5 ~ 150 μm, can be a single layer, can also be multi-layer.
Microencapsulation capsule wall materials generally used for natural polymer compounds or chemical synthesis of polymer materials. Extracted from natural substances, mainly gelatin, gum arabic, starch, beeswax, collagen, ethyl cellulose, amygdalin, chitin, etc., this kind of material viscosity, easy to form a film, good densification, non-toxic or very slightly toxic, but the mechanical properties of poor. Synthesized by chemical methods, such as polyvinyl alcohol, polystyrene, polyamide, polyurethane, polyurea, epoxy resin, etc., these materials have good mechanical properties, but poor biocompatibility. The most important characteristic of these substances is that they have certain film-forming properties and are relatively stable at room temperature, and the thickness of the capsule wall is generally 0.2 μm to several microns. When used should be based on the core of the capsule core material viscosity, permeability, chemical stability, hygroscopicity, solubility and other factors to determine the choice of what polymer materials for the wall material.
The preparation method of microcapsules is mainly divided into chemical method, physical-chemical method and physical method of 3 types. Chemical method is mainly the use of monomer polymerization of small molecules to generate polymer film-forming materials and the capsule core coating, common interface polymerization, in situ polymerization and emulsion polymerization method. Physicochemical method is mainly through changing the conditions, so that the dissolved state of the film-forming materials from the solution of the polymerization and precipitation, and the capsule core coating the formation of microcapsules, representative of the coalescence method of separation technology. Physical method is mainly the use of physical and mechanical principles for the preparation of microcapsules, this method has the advantages of simple equipment, low cost, easy to promote, conducive to large-scale continuous generation, etc., more mature air suspension coating method, spray drying method, extrusion, porous centrifugal method and so on.
Figure 3-7 shows the schematic diagram of microcapsule preparation by coalescence method, which applies the principle of coalescence phenomenon in colloid chemistry to prepare microcapsules.
Figure 3-7 The process of preparing microcapsules by coalescence method
① First, the microfine core material is dispersed into the microencapsulation medium;
② The film-forming material is then poured into this dispersion system;
③ By some method, the wall material is aggregated, deposited or encapsulated around the dispersed heart material;
④ The membrane wall of the microcapsule is unstable and still needs to be treated by chemical or physical methods to achieve a certain mechanical strength.
Microcapsules have more functions, in the printing of the main reduction of volatility, control of release, isolation of active ingredients, the formation of a good separation of the state and other functions. UV scented ink mainly using microcapsules to reduce volatility and control the release of the function, as the spice is wrapped by the film, the scent of the Xu Xu emanation, the scent of its preservation of up to one year; there are also scented microcapsules only in the ultraviolet irradiation, oxygen circulation, Some flavor microcapsules only in the ultraviolet radiation, oxygen circulation, heating, humidity changes and other environmental factors catalytic effect will react with each other to produce flavor substances, so that you can avoid the ineffective escape of the printed materials in general, but also to extend the time of the fragrance emitted.UV scented ink scent emitted by the temperature of the impact of the temperature, 25 ℃ below the emanation of slow, with the temperature rise emanation speed up. Ideally, the microcapsules are not easy to rupture during the printing process, but the finished product will emit flavor when touched by hand. This is because the printing pressure is generally in the microcapsule can withstand the pressure range, once the formation of printed products, due to the capsule and air contact, the capsule wall will be more or less oxidized, resulting in its ability to withstand the pressure becomes smaller, and at this time touching with the hand will emit a fragrance.
Due to the relatively coarse particles of microencapsulated ink, requiring the printing of the ink layer to be thicker, and printing can not be used to print a larger printing pressure, otherwise it will lead to microcapsule rupture, so there is a certain requirement for the printing method, usually using screen printing is more ideal. Because screen printing has some advantages, such as printing ink layer can be as thick as 100 ~ 300μm, its thickness is larger than the microcapsule particles, both on the microcapsule to play a protective role, but also to get other printing methods can not be obtained by the printing effect, it is fully capable of containing microcapsule ink transfer characteristics. In addition, screen printing is suitable for a variety of material properties and shape of the substrate, for the microcapsule technology to lay the foundation for a wide range of applications. In the selection of screen mesh to be clear about the relationship between the screen pore width and the volume of microcapsule particles in the ink, the general width of the screen mesh at least for the ink in the microcapsule (or filler) particles in the diameter of 3 ~ 4 times. UV scented inks used in the general diameter of the flavor of microcapsules in the 10 ~ 30 μm, so made of UV scented inks, the use of screen printing, the screen mesh selection of 200 ~ 300 mesh is more appropriate.
UV Fragrance Ink containing microcapsules rich in particles is more difficult to express the color and level of the picture, so try not to choose the original level is very rich, high clarity requirements of the picture as the original. Printing should pay attention to the control of the viscosity of the ink, ink containing microcapsules before printing viscosity adjustment, diluent should be appropriate, so that the microcapsule particles can be smoothly permeable without affecting its quality. Viscosity is too high, the ink is not easy to transfer to the substrate through the screen plate, resulting in printing difficulties, but the viscosity is too low will cause the print to expand, affecting the quality of printing, and even cause scrap. Printing speed in the printing process can not be too fast, so as not to scraper friction generated heat to make the temperature rise, resulting in the rupture of the microcapsule particles. In order to ensure that the ink can be smoothly transferred to the substrate through the screen holes, the adjustment of the printing pressure is very important, the printing pressure is too large will also cause the microcapsules rupture. In addition to pay attention to scraping the ink on the page after the ink is uniform, the use of different wall materials of microcapsules, printing should be combined with the printing effect of the use of different printing pressure. When a multi-color overlay printing, to combine the actual situation of specific arrangements, because not every color with microencapsulated particles, so it is necessary to reasonably arrange the color ink with microencapsulated particles of the color sequence. If the color ink containing microcapsules in the last color printing, can avoid the destruction of microencapsulated body later printing; but put in front of the printing, but also due to the later ink stacked up to play a role in protecting the release of microcapsules. Therefore, it should be rationally arranged in conjunction with the actual situation.
Fragrance ink spices should meet the following requirements:
① microcapsule rupture, spices and air contact more opportunities, so the spice should have a certain antioxidant capacity;
② water-soluble spices contain water, in order to avoid the spices have a greater impact on the ink, oil-soluble spices should be used;
③ spice volatility should be small, stability and durability should be good;
④ spices should be liquid;
⑤ The chemical properties of the spices should not be affected by the ink;
(vi) The cost should be as low as possible while meeting other conditions;
(vii) The capsule wall material should be oleophobic and have a certain degree of oxidation resistance.
The main points of the UV scented ink screen printing process are described below.
① scented ink screen printing screen selection. Should be used as far as possible nylon monofilament plain weave screen, because the nylon monofilament plain weave screen fiber surface smooth, with high elasticity and softness, good ink permeability. Mesh width of the screen should be at least greater than the diameter of the pigment particles in the ink 3 to 4 times.
② Points for screen printing with scented ink. Screen printing ink viscosity should be 2Pa-s or so, so the scented ink before printing viscosity adjustment, so that it reaches the required viscosity. The printing speed should not be too fast, so as to avoid the heat generated by the scraper friction, resulting in high temperature, leading to the rupture of the microcapsule particles (here the printing speed is the scraping speed). Printing pressure can not be too large, screen printing process in addition to pay attention to scraping ink on the layout after the ink is uniform, but also to observe whether the microcapsules rupture, smell there is no fragrance wafting out, so that, while trying to print, adjust the pressure. Color tone printing, should also consider the color sequence, containing microcapsules of color ink is best placed in the last printing, in order to avoid subsequent printing to destroy the microcapsule body.
Contact Us Now!
If you need Price, please fill in your contact information in the form below, we will usually contact you within 24 hours. You could also email me info@longchangchemical.com during working hours ( 8:30 am to 6:00 pm UTC+8 Mon.~Sat. ) or use the website live chat to get prompt reply.